Resistance of $0.2\; M$ solution of an electrolyte is $50 \Omega$ .
The specific conductance of the solution is $1.4 \;m^{-1}$ . The resistance of $0.5\; M$ solution of the same electrolyte is $280\Omega$ .The molar conductivity of $0.5\;M$ solution of the electrolyte in $S m^2mol^{-1}$ is :